maximum_icp_query_timeout

I described Squid's dynamic ICP/HTCP timeout algorithm under icp_query_timeout. If you'd like to use that algorithm, but wish to place an upper limit on the timeout, use the maximum_icp_query_timeout directive instead. Rather than a fixed timeout, Squid uses the dynamic timeout but makes sure it doesn't exceed the limit that you specify.

maximum_icp_query_timeout milliseconds

maximum_icp_query_timeout 3000